The Sputnik Double

The Sputnik or negative double is applied
and interpreted by the
program in its classic form. Put simply, partner doubles when he is
prevented by an opponent's intervention from making his intended bid

After an opening bid of 1 ♣ or 1 ♦,
followed
by an intervention of 1 ♠, partner's double promises a 4-card Heart
suit and at least 7 points

The double functions similarly at the 2-level. Thus
after an opening bid of 1 ♦,
followed
by an overcall of 2 ♣, partner's double promises a 4-card Spade
suit and at least 9 points

'Collante' is a further 'optional extra'. For example,
after a 1 ♣ opening, the double of an intervening 1 ♦ promises a 4-card
Heart suit and the double of an intervening 1 ♥
promises a 4-card Spade
suit. A direct response in a major thus promises a suit of at
least 5 cards

Collante also functions similarly at the 2-level. The
double of an intervening 2 ♦
promises a 4-card
Heart suit and the double of an intervening 2 ♥
promises a 4-card Spade
suit